This example shows a yellow smiley face rendered as an SVG, composed of a background circle, two eyes, and a mouth. The face is built using React components that wrap D3 functionality. The `arc` API from D3 generates the mouth’s path, while SVG `<circle>` elements handle the face and eyes. The code uses React’s `useState` implicitly through props, with D3 v5 and React 16.9, all positioned within a single `<g>` transform.